Triacylglycerols produced in plant tissues (e.g., canola seeds) are a significant source of fatty acids in the human diet. Diets rich in animal fat appear to promote maladies such as heart disease in humans. The ability to modulate triacylglycerol synthesis in plants could allow for production of fatty acid compositions that are more beneficial for humans or more efficiently synthesized by the plant. Cloning and characterization of plant genes encoding enzymes involved in triacylglycerol synthesis and metabolism represents a major advance toward controlling triacylglycerol synthesis in plants.